PHICH transmission in time division duplex systems

ABSTRACT

A method is provided for communication in a wireless telecommunication system. The method comprises multiplexing, by a network element, at least one symbol of a PHICH onto at least one resource element of a PCFICH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/658,576 filed Oct. 23, 2012 by Yiping Wang, et al. entitled, “PHICHTransmission in Time Division Duplex Systems” which claims priority toU.S. Provisional Application No. 61/645,939 filed May 11, 2012 by YipingWang, et al. entitled, “PHICH Transmission in Time Division DuplexSystems”, both of which are incorporated by reference herein as ifreproduced in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to control channels in wirelesstelecommunications systems.

BACKGROUND

As used herein, the term “user equipment” (alternatively “UE”) might insome cases refer to mobile devices such as mobile telephones, personaldigital assistants, handheld or laptop computers, and similar devicesthat have telecommunications capabilities. Such a UE might include adevice and its associated removable memory module, such as but notlimited to a Universal Integrated Circuit Card (UICC) that includes aSubscriber Identity Module (SIM) application, a Universal SubscriberIdentity Module (USIM) application, or a Removable User Identity Module(R-UIM) application. Alternatively, such a UE might include the deviceitself without such a module. In other cases, the term “UE” might referto devices that have similar capabilities but that are nottransportable, such as desktop computers, set-top boxes, or networkappliances. The term “UE” can also refer to any hardware or softwarecomponent that can terminate a communication session for a user. Also,the terms “user equipment,” “UE,” “user agent,” “UA,” “user device,” and“mobile device” might be used synonymously herein.

As telecommunications technology has evolved, more advanced networkaccess equipment has been introduced that can provide services that werenot possible previously. This network access equipment might includesystems and devices that are improvements of the equivalent equipment ina traditional wireless telecommunications system. Such advanced or nextgeneration equipment may be included in evolving wireless communicationsstandards, such as long-term evolution (LTE). For example, an LTE systemmight include an Evolved Universal Terrestrial Radio Access Network(E-UTRAN) node B (eNB), a wireless access point, or a similar componentrather than a traditional base station. Any such component will bereferred to herein as an eNB, but it should be understood that such acomponent is not necessarily an eNB. Such a component may also bereferred to herein as an access node.

LTE may be said to correspond to Third Generation Partnership Project(3GPP) Release 8 (Rel-8 or R8) and Release 9 (Rel-9 or R9), while LTEAdvanced (LTE-A) may be said to correspond to Release 10 (Rel-10 or R10)and possibly also to Release 11 (Rel-11 or R11) and other releasesbeyond Release 11. As used herein, the terms “legacy”, “legacy UE”, andthe like might refer to signals, UEs, and/or other entities that complywith LTE Release 10 and/or earlier releases but do not fully comply withreleases later than Release 10. The terms “advanced”, “advanced UE”, andthe like might refer to signals, UEs, and/or other entities that complywith LTE Release 11 and/or later releases. While the discussion hereindeals with LTE systems, the concepts are equally applicable to otherwireless systems as well.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a diagram of frequency division duplex and time divisionduplex modes.

FIG. 2 is a table showing LTE time division duplex uplink/downlinkconfigurations.

FIG. 3 is a diagram of a PHICH modulation process.

FIG. 4 is a diagram of a PCFICH modulation process.

FIG. 5 is a diagram of generation and detection of the PHICH and thePCFICH.

FIG. 6 is a diagram of uplink HARQ linkage in inter-band carrieraggregation with uplink/downlink configuration 1 on a PCell andconfiguration 0 on an SCell.

FIG. 7 is a simplified block diagram of an exemplary network elementaccording to one embodiment.

FIG. 8 is a block diagram with an example user equipment capable ofbeing used with the systems and methods in the embodiments describedherein.

FIG. 9 illustrates a processor and related components suitable forimplementing the several embodiments of the present disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although illustrativeimplementations of one or more embodiments of the present disclosure areprovided below, the disclosed systems and/or methods may be implementedusing any number of techniques, whether currently known or in existence.The disclosure should in no way be limited to the illustrativeimplementations, drawings, and techniques illustrated below, includingthe exemplary designs and implementations illustrated and describedherein, but may be modified within the scope of the appended claimsalong with their full scope of equivalents. Embodiments are describedherein in the context of an LTE wireless network or system, but can beadapted for other wireless networks or systems.

In an LTE system, downlink and uplink transmissions are organized intoone of two duplex modes, frequency division duplex (FDD) mode and timedivision duplex (TDD) mode. The FDD mode uses paired spectrum where thefrequency domain is used to separate the uplink (UL) and downlink (DL)transmissions. In TDD systems, on the other hand, unpaired spectrum isused where both UL and DL are transmitted over the same carrierfrequency. The UL and DL are separated in the time domain. FIG. 1illustrates both duplex modes.

In a 3GPP LTE TDD system, a subframe of a radio frame can be a downlink,an uplink or a special subframe. The special subframe comprises downlinkand uplink time regions separated by a guard period for downlink touplink switching. 3GPP Technical Specification (TS) 36.211 defines sevendifferent UL/DL configuration schemes in LTE TDD operations. The schemesare listed in FIG. 2, where D represents downlink subframes, Urepresents uplink subframes, and S represents a special frame. A specialframe includes three parts: the downlink pilot time slot (DwPTS), theuplink pilot time slot (UpPTS), and the guard period (GP). Downlinktransmissions on the Physical Downlink Shared Channel (PDSCH) may bemade in DL subframes or in the DwPTS portion of the special subframe.

As FIG. 2 shows, there are two switching point periodicities specifiedin the LTE standard, 5 milliseconds (ms) and 10 ms. 5 ms switching pointperiodicity is introduced to support the co-existence between LTE andlow chip rate UTRA TDD systems, and 10 ms switching point periodicity isfor the coexistence between LTE and high chip rate UTRA TDD systems. Thesupported configurations cover a wide range of UL/DL allocations from aDL-heavy 1:9 ratio to a UL-heavy 3:2 ratio. The DL allocations in theseratios include both DL subframes and special subframes, which can alsocarry downlink transmissions in the DwPTS. Compared to FDD, TDD systemshave more flexibility in terms of the proportion of resources assignableto uplink and downlink communications within a given assignment ofspectrum. Specifically, it is possible to distribute the radio resourcesunevenly between the uplink and the downlink. Such a distribution mayallow the radio resources to be utilized efficiently through theselection of an appropriate UL/DL configuration based on theinterference situation and different traffic characteristics in the DLand the UL.

The UL and DL transmissions may not be continuous in an LTE TDD system.That is, UL or DL transmissions may not occur in every subframe.Therefore, the data channel transmissions with their scheduling grantand Hybrid Automatic Repeat Request (HARQ) timing relationships areseparately defined in the 3GPP specifications. Currently, the HARQacknowledgement/negative acknowledgement (ACK/NACK) timing relationshipfor downlink data channel transmission is defined by Table 10.1.3.1-1 in3GPP TS 36.213. This timing relationship is shown in Table 1 below.Table 1 associates a UL ACK/NACK transmission at sub-frame n, with a DLPDSCH transmission at sub-frames n−ki, i=0 to M−1.

TABLE 1 Downlink HARQ association set index K: {k₀, k₁, . . . k_(M−1)}UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 41 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 —— 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — —5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

The uplink HARQ ACK/NACK timing linkage with the PUSCH transmission islisted in Table 8.3-1 of 3GPP TS 36.213, which is provided as Table 2below. Table 2 indicates that the Physical HARQ Indicator Channel(PHICH) carrying an ACK/NACK received in DL sub-frame i is linked withthe UL data transmission in UL sub-frame i−k, where k is given in Table2. For UL/DL configuration 0, in sub-frames 0 and 5, if I_(PHICH)=1,then k=6. Otherwise k=7. This is because there may be two ACK/NACKs fora UE transmitted on the PHICH in subframes 0 and 5.

TABLE 2 k for Uplink HARQ ACK/NACK association TDD UL/DL subframe numberi Configuration 0 1 2 3 4 5 6 7 8 9 0 7 or 6 4 7 or 6 4 1 4 6 4 6 2 6 63 6 6 6 4 6 6 5 6 6 6 4 7 4 6

The relationship of a UL grant and/or an ACK/NACK with a ULtransmission/retransmission is listed in Table 8.2 of 3GPP TS 36.213,which is provided as Table 3 below. The UE, upon detection of a PhysicalDownlink Control Channel (PDCCH) with Downlink Control Information (DCI)format 0 and/or a PHICH transmission in sub-frame n intended for the UE,sends the corresponding PUSCH transmission in sub-frame n+k, where k isgiven in Table 3.

TABLE 3 k for Uplink PUSCH grant association TDD UL/DL subframe number nConfiguration 0 1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 44 5 4 6 7 7 7 7 5

For TDD UL/DL configuration 0, if the Least Significant Bit (LSB) of theUL index in DCI format 0 is set to 1 in sub-frame n or a PHICH isreceived in sub-frame n=0 or 5 in the resource corresponding toI_(PHICH)=1 or a PHICH is received in sub-frame n=1 or 6, the UE sendsthe corresponding Physical Uplink Shared Channel (PUSCH) transmission insub-frame n+7. If, for TDD UL/DL configuration 0, both the MostSignificant Bit (MSB) and the LSB of the UL index in DCI format 0 areset to 1 in sub-frame n, the UE sends the corresponding PUSCHtransmission in both sub-frames n+k and n+7, where k is given in Table3.

It can be seen that both grant and HARQ timing linkage in TDD are morecomplicated than the fixed time linkages used in FDD. Accordingly, TDDusually requires more attention in design.

The PHICH specified in 3GPP TS 36.211 is used to transmit a HARQ-ACK,which indicates whether the eNB has correctly received UL shared channel(UL-SCH) data on the PUSCH. Multiple PHICHs can be transmitted in thesame set of resource elements as a PHICH group. In the same PHICH group,multiple PHICHs may be multiplexed with different complex orthogonalWalsh sequences. In the case of a normal cyclic prefix, eight PHICHs canbe multiplexed within one PHICH group as the length of the sequences isfour and the PHICHs are also multiplexed in the complex domain. For anextended cyclic prefix, four PHICHs can be multiplexed within a PHICHgroup with length-2 Walsh sequences. FIG. 3 illustrates the PHICHmodulation flow at the eNB.

For PHICH resource configuration, two parameters are signaled in theMaster Information Block (MIB): the PHICH duration and the number ofPHICH groups. The PHICH duration defines the number of OrthogonalFrequency Division Multiplexing (OFDM) symbols over which the PHICH isdistributed. To avoid a dependency on the Physical Control FormatIndicator Channel (PCFICH), the PHICH duration is independently signaledand can be different from the control region for the PDCCH. The numberof PHICH groups is used to define the amount of PHICH resources. Thecorrespondence between PHICH resources and UL-SCH transmission isimplicit. That is, there is a predefined representation rule between thePHICH resource index and the PUSCH Physical Resource Block (PRB) indextransmitting the UL-SCH. Because there is a PUSCH transmission without aPDCCH in the case of resource non-adaptive retransmission, a PHICHresource is linked to the actual PUSCH PRB index instead of the PDCCHControl Channel Element (CCE) index.

The PHICH resource is identified by the index pair (n)_(PHICH) ^(group),n_(PHICH) ^(seq)) where n_(PHICH) ^(group) is the PHICH group number andn_(PHICH) ^(seq) is the orthogonal sequence index within the group. AsPHICH resource is implicitly linked to the PUSCH PRB index that is usedto transmit the corresponding PUSCH, a UE may derive the assigned indexpair with the scheduled PUSCH PRB index. If a PHICH resource is smallerthan the number of PUSCH PRBs or if multiple users are scheduled in thesame PUSCH PRBs, a collision can happen. That is, the same PHICHresource may be assigned to multiple UEs. To avoid a collision, adifferent cyclic shift value that is indicated in the uplink DCI formatmay be used to derive the assigned PHICH resource. The followingequations are used to determine the PHICH group number and theorthogonal sequence index within the group:n _(PHICH) ^(group)=(I _(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index) +n_(DMRS))mod N _(PHICH) ^(group) +I _(PHICH) N _(PHICH) ^(group)n _(PHICH) ^(seq)=(└I _(PRB) _(_) _(Rd) ^(lowest) ^(_) ^(index) /N_(PHICH) ^(group) ┘+n _(DMRS))mod 2N _(SF) ^(PHICH)

In the above equations, n_(DMRS) is mapped from the cyclic shift for aDemodulation Reference Signal (DMRS) field according to the most recentPDCCH with uplink DCI format, as described in 3GPP TS 36.212 for thetransport block or blocks associated with the corresponding PUSCHtransmission. n_(DMRS) is set to zero if there is no PDCCH with uplinkDCI format for the same transport block, and if the initial PUSCH forthe same transport block is semi-persistently scheduled or if theinitial PUSCH for the same transport block is scheduled by a randomaccess response grant. N_(SF) ^(PHICH) is the spreading factor size usedfor PHICH modulation as described in section 6.9.1 of 3GPP TS 36.211.I_(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index) is the lowest PRB index inthe first slot of the corresponding PUSCH transmission. N_(PHICH)^(group) is the number of PHICH groups configured by higher layers asdescribed in section 6.9 of 3GPP TS 36.211.

$I_{PHICH} = \left\{ {\begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu}{TDD}\mspace{14mu}{{UL}/{DL}}\mspace{14mu}{configuration}\mspace{14mu} 0\mspace{14mu}{with}\mspace{14mu}{PUSCH}} \\{{{transmission}\mspace{14mu}{in}\mspace{14mu}{subframe}\mspace{14mu} n} = {4\mspace{14mu}{or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix}.} \right.$

For FDD, the index n_(PHICH) ^(group) ranges from 0 to N_(PHICH)^(group)−1. For TDD, the number of PHICH groups may vary betweendownlink subframes and is given by m_(i)·N_(PHICH) ^(group) where m, isgiven by Table 4. The index n_(PHICH) ^(group) in a downlink subframewith non-zero PHICH resources ranges from 0 to m_(i)·N_(PHICH)^(group)−1.

TABLE 4 The factor m_(i) for TDD Uplink-downlink Subframe number iconfiguration 0 1 2 3 4 5 6 7 8 9 0 2 1 — — — 2 1 — — — 1 0 1 — — 1 0 1— — 1 2 0 0 — 1 0 0 0 — 1 0 3 1 0 — — — 0 0 0 1 1 4 0 0 — — 0 0 0 0 1 15 0 0 — 0 0 0 0 0 1 0 6 1 1 — — — 1 1 — — 1

The PCFICH is currently used to indicate the number of OFDM symbols usedfor transmission of PDCCHs in each subframe. This number is called theControl Format Indicator (CFI). There are three different CFI code wordsused in the current version of LTE and a fourth one is reserved forfuture use. Each codeword is 32 bits in length. FIG. 4 illustrates thePCFICH modulation flow at an eNB.

In the current LTE specification, the PCFICH and the PHICH use differentresource elements. The PCFICH takes four Resource Element Groups (REGs)and the PHICH consumes three REGs. FIG. 5 shows the modulation chain atan eNB and the demodulation chain at a UE.

To meet LTE-A requirements, the Rel-10 LTE specification defines carrieraggregation (CA) for TDD systems. However, the Rel-10 specificationsupports CA only with the same UL/DL configuration on the aggregatedcarriers because intra-band CA is prioritized, and having differentUL/DL configurations is impossible to support in intra-band CA,especially when one single RF chain is used.

To achieve bandwidth flexibility and coexistence with legacy TDDsystems, inter-band carrier aggregation with different TDD UL/DLconfigurations on the carriers from different bands has been proposed inLTE Rel-11. Many design details, such as supporting both half duplex andfull duplex modes, supporting both separate scheduling (s-scheduling)and cross-carrier scheduling (c-scheduling), transmitting the PHICH onthe cell carrying the UL grant, and transmitting the PUCCH only on theprimary cell, have been agreed upon. Some agreements have also beenreached on HARQ timing linkage.

It should be noted that a component carrier (CC) is also known as aserving cell or a cell. Furthermore, when multiple CCs are scheduled,for each UE, one of the CCs is designated as the primary carrier whichis used for PUCCH transmission, semi-persistent scheduling, etc., whilethe remaining CCs are configured as secondary CCs. This primary carrieris also known as a PCell (Primary cell), while the secondary CC is knownas an SCell (Secondary cell).

As discussed above, the timing linkage in TDD systems is not as simpleas in FDD systems. The degree of complexity increases when CA withdifferent TDD configurations is considered. This is because, withdifferent TDD configurations, there are some time instances withconflicting subframes among aggregated CCs. For example, a UL subframeon CC1 may occur at the same time that CC2 has a DL subframe. Also, thetiming linkage may be different for each different TDD configurationand, furthermore, certain control signals may have to be on a specificcarrier. For example, the PHICH may have to be transmitted on the cellcarrying the UL grant. These conditions may lead to a need to transmit aPUSCH ACK/NACK at a DL subframe that does not have a PHICH resourceconfigured according to Table 4 above.

One of the 3GPP design agreements indicates that the PHICH can betransmitted only on the cell carrying the UL grant in the case ofinter-band CA with different UL/DL configurations. Therefore, a PUSCHACK/NACK may need to be transmitted at a DL subframe that does not havea PHICH resource configured.

In an example case, two TDD carriers may be aggregated, the PCell may beset as UL/DL configuration 1, and the SCell may have UL/DL configuration0, in full duplex mode. Based on the 3GPP design principles, the PCellfollows its own UL HARQ timing relationship, which is configuration 1,and the SCell UL HARQ follows the timing of configuration 0. In thiscase, the PCell with UL/DL configuration 1 is the scheduling cell andcarries the UL grant for the SCell, so the PUSCH ACK/NACK should be onthe PCell as well. FIG. 6 illustrates the UL HARQ timing of the abovescenario. The solid arrows represent the SCell UL grant fortransmission/retransmission, and the dashed arrows represent the ULHARQ-ACK timing of the SCell.

It can be seen that the ACK/NACK for PUSCH transmission at subframe #3or #4 of the SCell should be at subframe #0 of the PCell. However, withUL/DL configuration 1, referring to Table 4 above, there is no PHICHresource provisioned in the control region of PCell subframe #0. Thesame issue occurs for the PUSCH transmission at subframes #8 and #9 ofthe SCell. Additionally, there is no PHICH resource provisioned atsubframe #5 of the PCell.

Embodiments of the present disclosure can resolve these PHICH resourceissues by multiplexing the PHICH onto PCFICH resource elements. Theextra PHICH resources created by multiplexing the PHICH for the carrieraggregation UEs onto the PCFICH provide the capability to convey up tosix ACK/NACKs using PCFICH resource elements. These extra PHICHresources are recognized only by CA UEs, that is, UEs capable ofoperating under a carrier aggregation scenario. Legacy UEs can still usethe same resources defined in Rel 8/9/10. Therefore, these embodimentsare fully backward compatible.

In some cases, these embodiments may be used in conjunction with anadaptive retransmission procedure. In these cases, retransmission isdirectly triggered by a UL grant if there is a need for PUSCHretransmission. In this way, there is no need for an ACK/NACKtransmission if there is no PHICH resource provisioned in some DLsubframes.

In PCFICH generation, the scrambled bits are given by:{tilde over (b)} ^((CFT))(i)=(b ^((CFT))(i)+c(i))mod 2  (1)where b^((CFT))(i)∈{0,1} denotes the i-th bit in a CFI sequence for agiven CFI value; {c(i)} denotes the scrambling sequence initialized withc_(int)=(└n_(s)/2┘+1)·(2N_(ID) ^(cell)+1)·2⁹+N_(ID) ^(cell) at the startof each subframe; and {tilde over (b)}^((CFI))(i) is the i-th scrambledbit.

Quadrature phase shift keying (QPSK) modulation is used to generate ablock of 16 complex-valued symbols {d(k), k=0, 1, . . . , 15}.

TABLE 5 QPSK modulation mapping {tilde over (b)}^((CFI)) (i), {tildeover (b)}^((CFI)) (i + 1) I Q 00  1/{square root over (2)}  1/{squareroot over (2)} 01  1/{square root over (2)} −1/{square root over (2)} 10−1/{square root over (2)}  1/{square root over (2)} 11 −1/{square rootover (2)} −1/{square root over (2)}

It can be shown that the modulated PCFICH symbols can be written intothe following form:

$\begin{matrix}{{{d^{({PCFICH})}(k)} = {{\frac{1}{\sqrt{2}}{\left( {1 - {2 \cdot {b^{({CFI})}\left( {2k} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right)}} + {{j \cdot \frac{1}{\sqrt{2}}}{\left( {1 - {2 \cdot {b^{({CFI})}\left( {{2k} + 1} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right)}}}},\mspace{20mu}{k = 0},1,2,\ldots\mspace{14mu},15} & (2)\end{matrix}$

A PCFICH detection in general is a reversed operation of the PCFICHgeneration to find the one with the maximum energy of the followingpossible RxCFI correlations:

$\begin{matrix}{{y^{({RxCFI})} = {\left\lbrack {\sum\limits_{k = 0}^{15}\begin{matrix}{{Re}{\left\{ {x^{({PCFICH})}(k)} \right\} \cdot}} \\{\left( {1 - {2 \cdot {b^{({RxCFI})}\left( {2k} \right)}}} \right) \cdot} \\\left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right)\end{matrix}} \right\rbrack^{2} + \left\lbrack {\sum\limits_{k = 0}\overset{15}{\begin{matrix}{{Im}{\left\{ {x^{({PCFICH}}(k)} \right\} \cdot}} \\{\left( {1 - {2 \cdot {b^{({RxCFI})}\left( {{2k} + 1} \right)}}} \right) \cdot} \\\left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right)\end{matrix}}} \right\rbrack^{2}}},\mspace{20mu}{{RxCFI} = 0},1,2} & (3)\end{matrix}$where x^((PCFICH))(k) denotes the received signal at PCFICH RE k. It maybe noted that x^((PCFICH))(k)=d^((PCFICH))(k) in an ideal channel (nonoise, no fading, and no phase rotation). Also, it is possible to addthe real and imaginary parts and then take the square instead of takingthe squares separately and then summing.

The detected CFI is given by:

$\begin{matrix}{{CFI}_{detected} = {\underset{{RxCFI} \in {\{{0,1,2}\}}}{argmax}\left( y^{({RxCFI})} \right)}} & (4)\end{matrix}$

For the PHICH, the channel coding will generate a total of 12 coded bitswith three repeated sections, each section having a length of four. EachPHICH ACK/NACK bit will be repeated 12 times and then be binary phaseshift keying (BPSK) modulated, scrambled, and cover-coded with the PHICHorthogonal sequence. For a given PHICH sequence, the resulting symbolsare given by:

$\begin{matrix}{{{{d^{({PHICH})}(k)} = {\frac{1}{\sqrt{2}}\left( {1 + j} \right){{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{segldx}})}(k)}}} \right)} \cdot \left( {1 - {2 \cdot {c(k)}}} \right)}}},\mspace{20mu}{k = 0},1,2,\ldots\mspace{14mu},{11\mspace{14mu}\left( {{normal}\mspace{14mu}{CP}} \right)}}\mspace{20mu}{{k = 0},1,2,\ldots\mspace{14mu},{5\mspace{14mu}\left( {{extended}\mspace{14mu}{CP}} \right)}}} & (5)\end{matrix}$where w_(k) ^((seqIdx)) is the k-th element in the three-times-repeatedorthogonal sequence with sequence index seqIdx; b^((HI,seqIdx))(k) is aHI bit (for ACK/NACK) associated with sequence index seqIdx; and c(k) isa cell-specific scrambling sequence that is the same as that used forPCFICH generation.

The three-times-repeated orthogonal sequence is formed by repeating thecomplex orthogonal Walsh sequence [w(0) . . . w(N_(SF) ^(PHICH)−1)]three times and concatenating the sequences together. The complexorthogonal Walsh sequence is given by Table 6 below, where the sequenceindex seqIdx=n_(PHICH) ^(seq) corresponds to the PHICH number within thePHICH group.

TABLE 6 Orthogonal sequences [w(0) . . . w(N_(SF) ^(PHICH) − 1)] forPHICH. Orthogonal sequence Sequence index Normal cyclic Extended cyclicn_(PHICH) ^(seq) prefix N_(SF) ^(PHICH) = 4 prefix N_(SF) ^(PHICH) = 2 0[+1 +1 +1 +1] [+1 +1] 1 [+1 −1 +1 −1] [+1 −1] 2 [+1 +1 −1 −1] [+j +j] 3[+1 −1 −1 +1] [+j −j] 4 [+j +j +j +j] — 5 [+j −j +j −j] — 6 [+j +j −j−j] — 7 [+j −j −j +j] —

The transmitted PHICH symbols are a summation of PHICH symbols formultiple PHICH sequences in one PHICH group.

PHICH detection involves extracting the transmitted PHICH informationfrom the received channel-equalized symbols. Given a set of receivedsymbols {x(k)}, the decision variable for PHICH sequence RxSeqIdx can bewritten in the following form:

$\begin{matrix}{{{y^{({Rxseqldx})} = {{Re}\left\{ {\sum\limits_{k}{\left( {1 + j} \right)^{H}\left( w_{k}^{({seqldx})} \right)^{H}\left( {1 - {2 \cdot {c(k)}}} \right){x(k)}}} \right\}}},{k = 0},1,2,\ldots\mspace{14mu},{11\mspace{14mu}\left( {{normal}\mspace{14mu}{CP}} \right)}}{{k = 0},1,2,\ldots\mspace{14mu},{5\mspace{14mu}\left( {{extended}\mspace{14mu}{CP}} \right)}}} & (6)\end{matrix}$where the superscript H denotes a matrix Hermitian operation, which isequal to a conjugate transpose.

By comparing PCFICH generation Equation (2) and PHICH generationEquation (5), a sequence of PHICH symbols orthogonal to the sequence ofPCFICH symbols in Equation (2) can be formulated by removing the BPSKmodulation factor of (1+j) from Equation (5), replacing (1−2·c(k)) by(1−2·b^((CH))(2k))·(1−2·c(2k)) for real-valued w_(k) ^((seqIdx)),replacing (1−2·c(k)) by (1−2·b^((CFI))(2k+1))·(1−2·c(2k+1)) forimaginary-valued w_(k) ^((seqIdx)), and extending the length of PHICHspreading to 16 by repeating the HARQ indicator and Walsh sequence fourtimes instead of three times.

The resulting PHICH symbols are given by:

$\begin{matrix}{{d^{({PHICH})}(k)} = \left\{ \begin{matrix}{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {2k} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right)}\end{matrix},} & {{if}\mspace{14mu} w_{k}^{({seqldx})}\mspace{14mu}{is}\mspace{14mu}{real}} \\{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {{2k} + 1} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right)}\end{matrix},} & {otherwise}\end{matrix} \right.} & (7)\end{matrix}$

If Equation (7) is compared with Equation (2), it can be seen thatEquation (7) can be viewed as a generalized extension of the real orimaginary part of Equation (2) with an additional layer of covering codew_(k) ^((seqIdx))(1−2·b^((HI,seqIdx))(k)). On the other hand, Equation(2) is a special case of Equation (7) when b^((HI,sdqIdx))(k)=0 andw_(k) ^((seqIdx))=[1,1,1,1 . . . ] combined with the case whenb^((HI, seqIdx))(k)=0 and w_(k) ^((seqIdx))=[j,j,j,j, . . . ]. If anorthogonal Walsh sequence from Table 6, except sequence number 0[1,1,1,1] and sequence number 4 [j,j,j,j] for normal CP or sequencenumber 0 [1,1] and sequence number 2 [j,j] for extended CP, is used inEquation (7), and if the CFI hypothesis is correct, the sequence ofPHICH symbols defined in Equation (7) is orthogonal to the sequence ofPCFICH symbols defined in Equation (2).

As a result, the PHICH symbols defined in Equation (7) can betransmitted on top of PCFICH symbols defined in Equation (2) such thatthe PHICH and the PCFICH share the same set of resource elements. Thismay be useful in subframes where there is no provisioned resource forthe PHICH.

Since the newly added PHICH symbols are differentiated by the Walsh codeand orthogonal to the PCFICH symbols, this solution is backwardcompatible. Legacy UEs are still able to decode the PCFICH. According toCFI detection with Equations (3) and (4) and the orthogonality of theWalsh code, if the CFI hypothesis is correct, the overlay PHICHtransmission does not affect PCFICH correlation in additive whiteGaussian noise (AWGN) or when the frequency selectivity of the channelis not as severe. However, this overlay PHICH transmission may or maynot increase the correlation value of the CFI detection using Equations(3) and (4), when the CFI hypothesis is not correct. This may slightlydecrease the CFI detection performance. As the orthogonality of theWalsh code defined in Table 6 needs to be maintained just in one REG,and the four resource elements (REs) of one REG are closely located, itis expected that, in frequency selective fading channel cases, thissolution will have only a limited performance degradation compared tothe flat channel case. This performance degradation can be overcome byslightly increasing the transmit power on the PCFICH transmission.

CA UEs could make use of the extra power corresponding to the PHICHtransmission to improve their PCFICH detection.

After the PCFICH is correctly detected, the PHICH can be detected,similarly to Equation (6), by the following equation:

$y^{({Rxseqldx})} = \left\{ \begin{matrix}{{{Re}\left\{ {\sum\limits_{k}\begin{matrix}{\left( w_{k}^{({seqldx})} \right)^{H}{\left( {1 - {2 \cdot {b^{({CFI})}\left( {2k} \right)}}} \right) \cdot}} \\{\left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right){x(k)}}\end{matrix}} \right\}},} & {{if}\mspace{14mu} w_{k}^{({seqldx})}\mspace{14mu}{is}\mspace{14mu}{real}} \\{{{Re}\left\{ {\sum\limits_{k}\begin{matrix}{\left( w_{k}^{({seqldx})} \right)^{H}{\left( {1 - {2 \cdot {b^{({CFI})}\left( {{2k} + 1} \right)}}} \right) \cdot}} \\{\left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right){x(k)}}\end{matrix}} \right\}},} & {otherwise}\end{matrix} \right.$

In above equation, (1−2·b^((CH))(2k))·(1−2·c(2k)) or(1−2·b^((CH))(2k+1))·(1−2·c(2k+1)) can be treated as new scramblingsequences for the overlay PHICH transmission.

To achieve orthogonality between the overlaying PHICH transmission andthe PCFICH transmission, it can be seen that the number of sequencesavailable to carry PHICH bits is reduced to six from eight. Thissolution enables an eNB to multiplex six PUSCH HARQ indicators onto aPCFICH channel without using any extra resource elements. The peak toaverage power ratio (PAPR) in this combined PCFICH and PHICH is no worsethan in the existing PHICH.

In an embodiment, since there is only one PHICH group in this case andonly six PHICHs available, the mapping between the PUSCH and these newPHICHs may be given by:n _(PHICH) ^(seq)=(I _(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index) +n_(DMRS))mod Nwhere N is 6 for a normal cyclic prefix and 2 for an extended cyclicprefix. The other variables use the same notation as above.

The sequence index seqIdx=n_(PHICH) ^(seq) corresponding to the PHICHnumber is given by Table 7.

TABLE 7 Proposed orthogonal sequence to PHICH sequence index mapping.Orthogonal sequence Sequence index Normal cyclic Extended cyclicn_(PHICH) ^(seq) prefix N_(SF) ^(PHICH) = 4 prefix N_(SF) ^(PHICH) = 2 0[+1 −1 +1 −1] [+1 −1] 1 [+1 +1 −1 −1] [+j −j] 2 [+1 −1 −1 +1] — 3 [+j −j+j −j] — 4 [+j +j −j −j] — 5 [+j −j −j +j] —

Alternatively, explicit signaling can be used to define the mappingbetween the PUSCH and these new PHICH bits.

In an embodiment, if there are more than six PHICH bits, the first sixbits can use the approach described above and the rest can rely on anadaptive retransmission procedure. The adaptive retransmission procedureuses a UL grant to instruct UEs regarding PUSCH retransmission. ACK/NACKinformation can be implicitly conveyed in this procedure, so there is noneed for ACK/NACK transmission in DL subframes. Legacy UEs will not beimpacted, since this procedure is UE-specific. Moreover, legacy UEscould also use this scheme if needed.

In an embodiment, the UL grant uses DCI format 0 transmitted in thePDCCH and contains a New Data Indicator (NDI). Whenever a new packettransmission begins, the one-bit NDI is toggled. For indication ofretransmission, the one-bit NDI is kept at the same value as in theprevious DCI 0 grant for the same HARQ process. The UE receives the ULgrant and compares the NDI with the previously received grant's NDI. Ifthe NDIs are the same, the UE knows that the UL grant is for theretransmission of the UL-SCH data on the previous PUSCH.

With adaptive retransmission, the retransmission Physical Resource Block(PRB) can be different from the initial PUSCH PRB. This provides anopportunity to choose more desirable radio resources based on thecurrent radio channel conditions and may lead to better performance.However, since the UL grant is UE-specific, it may become costly, interms of PDCCH resources, if there are a significant number ofretransmissions relying on this scheme. Operators could apply a policyto restrict the feature to important users with high quality of servicerequirements.

The above may be implemented by a network element. A simplified networkelement is shown with regard to FIG. 7. In FIG. 7, network element 3110includes a processor 3120 and a communications subsystem 3130, where theprocessor 3120 and communications subsystem 3130 cooperate to performthe methods described above.

Further, the above may be implemented by a UE. An example of a UE isdescribed below with regard to FIG. 8. UE 3200 may comprise a two-waywireless communication device having voice and data communicationcapabilities. In some embodiments, voice communication capabilities areoptional. The UE 3200 generally has the capability to communicate withother computer systems on the Internet. Depending on the exactfunctionality provided, the UE 3200 may be referred to as a datamessaging device, a two-way pager, a wireless e-mail device, a cellulartelephone with data messaging capabilities, a wireless Internetappliance, a wireless device, a smart phone, a mobile device, or a datacommunication device, as examples.

Where the UE 3200 is enabled for two-way communication, it mayincorporate a communication subsystem 3211, including a receiver 3212and a transmitter 3214, as well as associated components such as one ormore antenna elements 3216 and 3218, local oscillators (LOs) 3213, and aprocessing module such as a digital signal processor (DSP) 3220. Theparticular design of the communication subsystem 3211 may be dependentupon the communication network in which the UE 3200 is intended tooperate.

Network access requirements may also vary depending upon the type ofnetwork 3219. In some networks, network access is associated with asubscriber or user of the UE 3200. The UE 3200 may require a removableuser identity module (RUIM) or a subscriber identity module (SIM) cardin order to operate on a network. The SIM/RUIM interface 3244 istypically similar to a card slot into which a SIM/RUIM card may beinserted. The SIM/RUIM card may have memory and may hold many keyconfigurations 3251 and other information 3253, such as identificationand subscriber-related information.

When required network registration or activation procedures have beencompleted, the UE 3200 may send and receive communication signals overthe network 3219. As illustrated, the network 3219 may consist ofmultiple base stations communicating with the UE 3200.

Signals received by antenna 3216 through communication network 3219 areinput to receiver 3212, which may perform such common receiver functionsas signal amplification, frequency down conversion, filtering, channelselection, and the like. Analog to digital (A/D) conversion of areceived signal allows more complex communication functions, such asdemodulation and decoding to be performed in the DSP 3220. In a similarmanner, signals to be transmitted are processed, including modulationand encoding for example, by DSP 3220 and are input to transmitter 3214for digital to analog (D/A) conversion, frequency up conversion,filtering, amplification, and transmission over the communicationnetwork 3219 via antenna 3218. DSP 3220 not only processes communicationsignals but also provides for receiver and transmitter control. Forexample, the gains applied to communication signals in receiver 3212 andtransmitter 3214 may be adaptively controlled through automatic gaincontrol algorithms implemented in DSP 3220.

The UE 3200 generally includes a processor 3238 which controls theoverall operation of the device. Communication functions, including dataand voice communications, are performed through communication subsystem3211. Processor 3238 also interacts with further device subsystems suchas the display 3222, flash memory 3224, random access memory (RAM) 3226,auxiliary input/output (I/O) subsystems 3228, serial port 3230, one ormore keyboards or keypads 3232, speaker 3234, microphone 3236, othercommunication subsystem 3240 such as a short-range communicationssubsystem, and any other device subsystems generally designated as 3242.Serial port 3230 may include a USB port or other port currently known ordeveloped in the future.

Some of the illustrated subsystems perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 3232 and display3222, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork, and device-resident functions, such as a calculator or tasklist.

Operating system software used by the processor 3238 may be stored in apersistent store such as flash memory 3224, which may instead be aread-only memory (ROM) or similar storage element (not shown). Theoperating system, specific device applications, or parts thereof, may betemporarily loaded into a volatile memory such as RAM 3226. Receivedcommunication signals may also be stored in RAM 3226.

As shown, flash memory 3224 may be segregated into different areas forboth computer programs 3258 and program data storage 3250, 3252, 3254and 3256. These different storage types indicate that each program mayallocate a portion of flash memory 3224 for their own data storagerequirements. Processor 3238, in addition to its operating systemfunctions, may enable execution of software applications on the UE 3200.A predetermined set of applications that control basic operations,including at least data and voice communication applications forexample, may typically be installed on the UE 3200 during manufacturing.Other applications may be installed subsequently or dynamically.

Applications and software may be stored on any computer-readable storagemedium. The computer-readable storage medium may be tangible or in atransitory/non-transitory medium such as optical (e.g., CD, DVD, etc.),magnetic (e.g., tape), or other memory currently known or developed inthe future.

One software application may be a personal information manager (PIM)application having the ability to organize and manage data itemsrelating to the user of the UE 3200 such as, but not limited to, e-mail,calendar events, voice mails, appointments, and task items. One or morememory stores may be available on the UE 3200 to facilitate storage ofPIM data items. Such a PIM application may have the ability to send andreceive data items via the wireless network 3219. Further applicationsmay also be loaded onto the UE 3200 through the network 3219, anauxiliary I/O subsystem 3228, serial port 3230, short-rangecommunications subsystem 3240, or any other suitable subsystem 3242, andinstalled by a user in the RAM 3226 or a non-volatile store (not shown)for execution by the processor 3238. Such flexibility in applicationinstallation may increase the functionality of the UE 3200 and mayprovide enhanced on-device functions, communication-related functions,or both. For example, secure communication applications may enableelectronic commerce functions and other such financial transactions tobe performed using the UE 3200.

In a data communication mode, a received signal such as a text messageor web page download may be processed by the communication subsystem3211 and input to the processor 3238, which may further process thereceived signal for output to the display 3222, or alternatively to anauxiliary I/O device 3228.

A user of the UE 3200 may also compose data items, such as emailmessages for example, using the keyboard 3232, which may be a completealphanumeric keyboard or telephone-type keypad, among others, inconjunction with the display 3222 and possibly an auxiliary I/O device3228. Such composed items may then be transmitted over a communicationnetwork through the communication subsystem 3211.

For voice communications, overall operation of the UE 3200 is similar,except that received signals may typically be output to a speaker 3234and signals for transmission may be generated by a microphone 3236.Alternative voice or audio I/O subsystems, such as a voice messagerecording subsystem, may also be implemented on the UE 3200. Althoughvoice or audio signal output may be accomplished primarily through thespeaker 3234, display 3222 may also be used to provide an indication ofthe identity of a calling party, the duration of a voice call, or othervoice call-related information, for example.

Serial port 3230 may be implemented in a personal digital assistant(PDA)-type device for which synchronization with a user's desktopcomputer (not shown) may be desirable, but such a port is an optionaldevice component. Such a port 3230 may enable a user to set preferencesthrough an external device or software application and may extend thecapabilities of the UE 3200 by providing for information or softwaredownloads to the UE 3200 other than through a wireless communicationnetwork. The alternate download path may, for example, be used to loadan encryption key onto the UE 3200 through a direct and thus reliableand trusted connection to thereby enable secure device communication.Serial port 3230 may further be used to connect the device to a computerto act as a modem.

Other communications subsystems 3240, such as a short-rangecommunications subsystem, are further optional components which mayprovide for communication between the UE 3200 and different systems ordevices, which need not necessarily be similar devices. For example, thesubsystem 3240 may include an infrared device and associated circuitsand components or a Bluetooth™ communication module to provide forcommunication with similarly enabled systems and devices. Subsystem 3240may further include non-cellular communications such as WiFi, WiMAX,near field communication (NFC), and/or radio frequency identification(RFID). The other communications element 3240 may also be used tocommunicate with auxiliary devices such as tablet displays, keyboards orprojectors.

The UE and other components described above might include a processingcomponent that is capable of executing instructions related to theactions described above. FIG. 9 illustrates an example of a system 3300that includes a processing component 3310 suitable for implementing oneor more embodiments disclosed herein. In addition to the processor 3310(which may be referred to as a central processor unit or CPU), thesystem 3300 might include network connectivity devices 3320, randomaccess memory (RAM) 3330, read only memory (ROM) 3340, secondary storage3350, and input/output (I/O) devices 3360. These components mightcommunicate with one another via a bus 3370. In some cases, some ofthese components may not be present or may be combined in variouscombinations with one another or with other components not shown. Thesecomponents might be located in a single physical entity or in more thanone physical entity. Any actions described herein as being taken by theprocessor 3310 might be taken by the processor 3310 alone or by theprocessor 3310 in conjunction with one or more components shown or notshown in the drawing, such as a digital signal processor (DSP) 3380.Although the DSP 3380 is shown as a separate component, the DSP 3380might be incorporated into the processor 3310.

The processor 3310 executes instructions, codes, computer programs, orscripts that it might access from the network connectivity devices 3320,RAM 3330, ROM 3340, or secondary storage 3350 (which might includevarious disk-based systems such as hard disk, floppy disk, or opticaldisk). While only one CPU 3310 is shown, multiple processors may bepresent. Thus, while instructions may be discussed as being executed bya processor, the instructions may be executed simultaneously, serially,or otherwise by one or multiple processors. The processor 3310 may beimplemented as one or more CPU chips.

The network connectivity devices 3320 may take the form of modems, modembanks, Ethernet devices, universal serial bus (USB) interface devices,serial interfaces, token ring devices, fiber distributed data interface(FDDI) devices, wireless local area network (WLAN) devices, radiotransceiver devices such as code division multiple access (CDMA)devices, global system for mobile communications (GSM) radio transceiverdevices, universal mobile telecommunications system (UMTS) radiotransceiver devices, long term evolution (LTE) radio transceiverdevices, worldwide interoperability for microwave access (WiMAX)devices, and/or other well-known devices for connecting to networks.These network connectivity devices 3320 may enable the processor 3310 tocommunicate with the Internet or one or more telecommunications networksor other networks from which the processor 3310 might receiveinformation or to which the processor 3310 might output information. Thenetwork connectivity devices 3320 might also include one or moretransceiver components 3325 capable of transmitting and/or receivingdata wirelessly.

The RAM 3330 might be used to store volatile data and perhaps to storeinstructions that are executed by the processor 3310. The ROM 3340 is anon-volatile memory device that typically has a smaller memory capacitythan the memory capacity of the secondary storage 3350. ROM 3340 mightbe used to store instructions and perhaps data that are read duringexecution of the instructions. Access to both RAM 3330 and ROM 3340 istypically faster than to secondary storage 3350. The secondary storage3350 is typically comprised of one or more disk drives or tape drivesand might be used for non-volatile storage of data or as an over-flowdata storage device if RAM 3330 is not large enough to hold all workingdata. Secondary storage 3350 may be used to store programs that areloaded into RAM 3330 when such programs are selected for execution.

The I/O devices 3360 may include liquid crystal displays (LCDs), touchscreen displays, keyboards, keypads, switches, dials, mice, track balls,voice recognizers, card readers, paper tape readers, printers, videomonitors, or other well-known input/output devices. Also, thetransceiver 3325 might be considered to be a component of the I/Odevices 3360 instead of or in addition to being a component of thenetwork connectivity devices 3320.

In an embodiment, a method for communication in a wirelesstelecommunication system is provided. The method comprises multiplexing,by a network element, at least one symbol of a PHICH onto at least oneresource element of a PCFICH.

In another embodiment, a network element is provided. The networkelement comprises a processor configured such that the network elementmultiplexes at least one symbol of a PHICH onto at least one resourceelement of a PCFICH.

The following are incorporated herein by reference for all purposes:3GPP TS 36.211, 3GPP TS 36.212, and 3GPP TS 36.213.

The embodiments described herein are examples of structures, systems ormethods having elements corresponding to elements of the techniques ofthis application. This written description may enable those skilled inthe art to make and use embodiments having alternative elements thatlikewise correspond to the elements of the techniques of thisapplication. The intended scope of the techniques of this applicationthus includes other structures, systems or methods that do not differfrom the techniques of this application as described herein, and furtherincludes other structures, systems or methods with insubstantialdifferences from the techniques of this application as described herein.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods may beembodied in many other specific forms without departing from the scopeof the present disclosure. The present examples are to be considered asillustrative and not restrictive, and the intention is not to be limitedto the details given herein. For example, the various elements orcomponents may be combined or integrated in another system or certainfeatures may be omitted, or not implemented.

Also, techniques, systems, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component, whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method for communication in a wirelesstelecommunication system, the method comprising: multiplexing, by anetwork element, at least one symbol of a physical HARQ (hybridautomatic repeat request) indicator channel (PHICH) onto at least oneresource element of a physical control format indicator channel(PCFICH), wherein the at least one resource element is shared by thePHICH and the PCFICH, wherein extra PHICH resources are created in acontrol region of a subframe by multiplexing the at least one PHICHsymbol onto the at least one PCFICH resource element such that up to sixacknowledgement/negative acknowledgement (ACK/NACK) signals can becarried using the extra PHICH resources, wherein the at least one PHICHsymbol is orthogonal to at least one PCFICH symbol.
 2. The method ofclaim 1, wherein the at least one PHICH symbol is mapped to a physicaluplink shared channel (PUSCH) by the following equation:n _(PHICH) ^(seq)=(I _(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index) +n_(DMRS))mod N where N is 6 for a normal cyclic prefix and N is 2 for anextended cyclic prefix.
 3. The method of claim 2, wherein explicitsignaling is used to define the mapping between the PUSCH and the atleast one PHICH symbol.
 4. The method of claim 1, wherein channel codingfor the PHICH generates a total of 16 coded bits with four repeatedsections, each section having a length of four for normal cyclic prefixmode and a length of two for extended cyclic prefix mode, and whereineach PHICH acknowledgement/negative acknowledgement (ACK/NACK) bit isrepeated 16 times and then binary phase shift keying (BPSK) modulated,scrambled, and cover-coded with the PHICH orthogonal sequence.
 5. Themethod of claim 4, wherein, for a given PHICH sequence, the resultingsymbols are given by: ${d^{({PHICH})}(k)} = \left\{ \begin{matrix}{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {2k} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right)}\end{matrix},} & {{if}\mspace{14mu} w_{k}^{({seqldx})}\mspace{14mu}{is}\mspace{14mu}{real}} \\{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {{2k} + 1} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right)}\end{matrix},} & {otherwise}\end{matrix} \right.$ where w_(k) ^((seqIdx)) is the k-th element in thefour-times-repeated orthogonal sequence with sequence index seqIdx;b^((HI,seqIdx))(k) is a HI bit (for ACK/NACK) associated with sequenceindex seqIdx; b^((CFT))(i)∈{0,1} for i=2k and 2k+1 denotes the i-th bitin a Control Format Indicator (CFI) sequence for a given CFI value; andc(k) is a cell-specific scrambling sequence that is the same as thatused for PCFICH generation.
 6. The method of claim 4, wherein thefour-times-repeated orthogonal sequence is formed by repeating thecomplex orthogonal Walsh sequence [w(0) . . . w(N_(SF) ^(PHICH)−1)] fourtimes and concatenating the sequences together.
 7. The method of claim1, wherein power on the PCFICH is increased to overcome performancedegradation caused by the multiplexing of the PHICH and the PCFICH. 8.The method of claim 1, wherein the network element includes, in anuplink grant to a transmitting entity, a new data indicator capable ofassuming one of two different values, wherein the network elementchanges the value of the new data indicator when the network elementrequests a new data transmission from the transmitting entity, andwherein the network element does not change the value of the new dataindicator when the network element requests a retransmission from thetransmitting entity.
 9. The method of claim 1, further comprising thenetwork element including a new data indicator in an uplink grant to atransmitting entity when the number of PHICH bits to be transmitted isgreater than the number of PHICH bits that can be multiplexed onto thePCFICH.
 10. The method of claim 1, wherein the network element is aprimary cell in a wireless telecommunication system that employs carrieraggregation.
 11. A network element in a wireless telecommunicationsystem, the network element comprising: a processor configured such thatthe network element multiplexes at least one symbol of a physical HARQ(hybrid automatic repeat request) indicator channel (PHICH) onto atleast one resource element of a physical control format indicatorchannel (PCFICH), wherein the at least one resource element is shared bythe PHICH and the PCFICH, wherein extra PHICH resources are created in acontrol region of a subframe by multiplexing the at least one PHICHsymbol onto the at least one PCFICH resource element such that up to sixacknowledgement/negative acknowledgement (ACK/NACK) signals can becarried using the extra PHICH resources, wherein the at least one PHICHsymbol is orthogonal to at least one PCFICH symbol.
 12. The networkelement of claim 11, wherein the at least one PHICH symbol is mapped toa physical uplink shared channel (PUSCH) by the following equation:n _(PHICH) ^(seq)=(I _(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index) +n_(DMRS))mod N where N is 6 for a normal cyclic prefix and 2 for anextended cyclic prefix.
 13. The network element of claim 12, whereinexplicit signaling is used to define the mapping between the PUSCH andthe at least one PHICH symbol.
 14. The network element of claim 11,wherein channel coding for the PHICH generates a total of 16 coded bitswith four repeated sections, each section having a length of four fornormal cyclic prefix mode and a length of two for extended cyclic prefixmode, and wherein each PHICH acknowledgement/negative acknowledgement(ACK/NACK) bit is repeated 16 times and then binary phase shift keying(BPSK) modulated, scrambled, and cover-coded with the PHICH orthogonalsequence.
 15. The network element of claim 14, wherein, for a givenPHICH sequence, the resulting symbols are given by:${d^{({PHICH})}(k)} = \left\{ \begin{matrix}{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {2k} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {2k} \right)}}} \right)}\end{matrix},} & {{if}\mspace{14mu} w_{k}^{({seqldx})}\mspace{14mu}{is}\mspace{14mu}{real}} \\{\begin{matrix}{\frac{1}{\sqrt{2}}{{w_{k}^{({seqldx})}\left( {1 - {2 \cdot {b^{({{HI},{seqldx}})}(k)}}} \right)} \cdot}} \\{\left( {1 - {2 \cdot {b^{({CFI})}\left( {{2k} + 1} \right)}}} \right) \cdot \left( {1 - {2 \cdot {c\left( {{2k} + 1} \right)}}} \right)}\end{matrix},} & {otherwise}\end{matrix} \right.$ where w_(k) ^((seqIdx)) is the k-th element in thefour-times-repeated orthogonal sequence with sequence index seqIdx;b^((HI,seqIdx))(k) is a HI bit (for ACK/NACK) associated with sequenceindex seqIdx; b^((CFT))(i)∈{0,1} for i=2k and 2k+1 denotes the i-th bitin a Control Format Indicator (CFI) sequence for a given CFI value; andc(k) is a cell-specific scrambling sequence that is the same as thatused for PCFICH generation.
 16. The network element of claim 14, whereinthe four-times-repeated orthogonal sequence is formed by repeating thecomplex orthogonal Walsh sequence [w(0) . . . w(N_(SF) ^(PHICH)−1)] fourtimes and concatenating the sequences together.
 17. The network elementof claim 11, wherein power on the PCFICH is increased to overcomeperformance degradation caused by the multiplexing of the PHICH and thePCFICH.
 18. The network element of claim 11, wherein the network elementincludes, in an uplink grant to a transmitting entity, a new dataindicator capable of assuming one of two different values, wherein thenetwork element changes the value of the new data indicator when thenetwork element requests a new data transmission from the transmittingentity, and wherein the network element does not change the value of thenew data indicator when the network element requests a retransmissionfrom the transmitting entity.
 19. The network element of claim 11,wherein the network element includes a new data indicator in an uplinkgrant to a transmitting entity when the number of PHICH bits to betransmitted is greater than the number of PHICH bits that can bemultiplexed onto the PCFICH.
 20. The network element of claim 11,wherein the network element is a primary cell in a wirelesstelecommunication system that employs carrier aggregation.